首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   693篇
  免费   61篇
  国内免费   3篇
耳鼻咽喉   6篇
儿科学   30篇
妇产科学   9篇
基础医学   106篇
口腔科学   78篇
临床医学   66篇
内科学   155篇
皮肤病学   13篇
神经病学   81篇
特种医学   24篇
外科学   58篇
综合类   4篇
预防医学   40篇
眼科学   24篇
药学   14篇
肿瘤学   49篇
  2023年   4篇
  2022年   11篇
  2021年   7篇
  2020年   13篇
  2019年   11篇
  2018年   23篇
  2017年   24篇
  2016年   34篇
  2015年   21篇
  2014年   22篇
  2013年   39篇
  2012年   54篇
  2011年   50篇
  2010年   32篇
  2009年   30篇
  2008年   62篇
  2007年   39篇
  2006年   61篇
  2005年   45篇
  2004年   34篇
  2003年   33篇
  2002年   24篇
  2001年   16篇
  2000年   7篇
  1999年   6篇
  1998年   5篇
  1997年   4篇
  1996年   6篇
  1995年   3篇
  1994年   7篇
  1993年   3篇
  1992年   5篇
  1991年   1篇
  1990年   2篇
  1989年   4篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   5篇
  1984年   1篇
  1983年   1篇
  1978年   1篇
排序方式: 共有757条查询结果,搜索用时 0 毫秒
1.
2.
In this cross-sectional study, we evaluated the cervical spine in patients with diastrophic dysplasia (DD) by using magnetic resonance imaging (MRI). From 90 (57 female, 33 male) patients of different ages (0.3-56.0 years), T1- and T2-weighted images were obtained. The craniocervical junction and status of the medulla were examined, and the transverse areas of dural tube and medulla were measured. Alignment of the cervical spine, vertebral abnormalities, and disc changes also were evaluated. The cervical spinal canal was moderately narrowed, particularly in adults. The transverse areas of the medulla and especially of the dural tube were smaller compared with a normal population (p < 0.0001). There was no stenosis of the foramen magnum in patients with DD, but the spinal canal was narrowed. Degenerative changes were common. In all age groups, intervertebral discs were dark and disc heights were narrowed. Three (3%) patients (two children, one adult) had cervical kyphosis. Compression of the medulla was noted in association with severe cervical kyphosis in one child and one adult. Typical findings of the cervical spine in DD were exceptionally wide foramen magnum, narrowed spinal canal and early degenerative changes, and in older age groups, especially midcervically narrowed spinal canal. Severe cervical kyphosis caused medullar compression. The intervertebral discs developed abnormally. Abnormal disc structure may be one etiologic factor in the development of cervical kyphosis. Early and rapid progression of the degenerative changes is a normal finding in patients with DD, regardless of their age, and this also explains the stiffness of the cervical spine in clinical examination.  相似文献   
3.
The way in which retirement is conceptualized and measured is likely to influence the research findings. The previous literature has addressed a wide range of elements related to the complex work-to-retirement process, such as early, late and partial retirement, statutory retirement, work disability and unemployment paths to retirement, or different types of bridge employment. However, conceptual clarity in terms of connections between the different elements is called for. We introduce a conceptual framework of the work-to-retirement process to guide its future measurement. Together with information on the statutory retirement age, the main elements of the framework are based on employment and pension receipt, acknowledging that these may overlap. The framework is flexible to the user, providing the possibility to add various specifications—e.g. of types of employment, types of pension receipt, unemployment, and being outside the labour force—depending on the study context and aims. The framework highlights the complexity of the work-to-retirement process, bringing forth its multifaceted, multiphased and multidirectional features. Accounting for such complexity in later-life labour market dynamics helps to elaborate what is actually addressed when investigating “retirement”. Our conceptual framework can be utilized to enhance well-defined, precise and comparable measurement of the work-to-retirement process in studies.  相似文献   
4.
ObjectivesThe aim of this discussion paper is to (i) identify the differentiated roles of health in the work–retirement transition, and, with respect to these, (ii) highlight topics related to conceptual and methodological problems and challenges in research, and (iii) present avenues for future research.MethodsThis discussion paper summarizes an OMEGA-NET working group discussion ongoing from November 2018 to September 2021 with face-to-face and online meetings as well as a written online discourse.Results‘Health’ and ‘retirement’ are ambiguous concepts. With respect to both, in retirement research, the choice of concept and indicator influences the findings. In addition, the impact of health on retirement is not necessarily a direct one, but can be influenced by further factors such as the ability, motivation and opportunity to work. The strong overall association of poor health with retiring early (path 1) bears the risk of masking distinct and deviating mechanisms in subgroups. In fact, there is evidence that also good health may lead to early retirement (path 2), while both poor health (path 3) and good health (path 4) may also make people retire later.ConclusionsAn increased awareness of the differentiated roles that health may have in the work–retirement transition as outlined in this discussion paper may support research to address questions relevant for policy and practice and increase the impact of research. Recommendations for occupational health and social research are given.  相似文献   
5.
6.
7.
8.
BACKGROUND: Decreased fitness of the lower extremities is a potentially modifiable fall risk factor. This study aimed to compare two exercise programs--square-stepping exercise (SSE), which is a low-cost indoor program, and walking--for improving the fitness of the lower extremities. METHODS: We randomly allocated 68 community-dwelling older adults (age 65-74 years) to either the SSE or walking group (W group). During the 12-week regimen, the SSE group participated in 70-minute exercise sessions conducted twice a week at a local health center, and the W group participated in outdoor supervised walking sessions conducted weekly. The W group was instructed to increase the number of daily steps. Prior to and after the program, we obtained information on 11 physical performance tests for known fall risk factors and 3 self-reported scales. The fall incidence was followed-up for 8 months. RESULTS: At 12 weeks postregimen, significant differences were observed between the two exercise groups with respect to leg power (1 item), balance (2 items), agility (2 items), reaction time (2 items), and a self-reported scale (1 item); the SSE group demonstrated a marked improvement in the above-mentioned items with Group x Time interactions. Significant time effects were observed in the tests involving chair stands, functional reach, and standing up from a lying-down position without Group x Time interactions. During the follow-up period, the fall rates per person-year in the SSE and W groups were 23.4% and 33.3%, respectively (p =.31). CONCLUSION: Although further studies are required, SSE is apparently more effective than walking in reducing fall risk factors, and it appears that it may be recommended as a health promotion exercise in older adults.  相似文献   
9.
10.
Obstructive sleep apnea (OSA) is linked to an increased mortality rate. However, the severity of individual obstruction events is rarely considered quantitatively in clinical practice. We hypothesized that OSA with especially severe obstruction events would predispose a patient to greater health risks than OSA with a similar apnea–hypopnea index (AHI), but lower severity of individual events. This hypothesis was tested in a follow‐up (198.2 ± 24.7 months) of a population of 1068 men referred for ambulatory polygraphic recording due to suspected OSA. The recordings were analysed according to the guidelines of the American Academy of Sleep Medicine. Furthermore, a novel obstruction severity parameter was determined; this was defined as the product of duration of the individual obstruction event and area of the related desaturation event. Patients treated with continuous positive airway pressure (CPAP) were omitted. We identified 125 deceased patients from our original population and for 113 of these a matching alive patient with similar AHI, age, body mass index (BMI), smoking habits and follow‐up time could be found. The deceased patients with severe OSA (based on conventional AHI) showed higher obstruction severity values than their AHI‐matched alive controls. Based on the multivariate logistic regression analysis, obstruction severity was the only parameter which was related statistically significantly to mortality in the severe OSA category. Furthermore, 59% of all deceased patients and 83% of those who had severe OSA displayed higher obstruction severity than the AHI‐matched alive counterparts. To conclude, the obstruction severity parameter provided valuable prognostic information supplementing AHI. The obstruction severity parameter might improve recognition of the patients with the highest risk.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号